Thanks for posting.
Adding new user accounts will take place in the databases themselves. Here's a quick description of the process:
1. Go to FileMaker Server Admin Console > Databases
2. Close the database(s) by Right-Clicking (Win) or Ctrl + Click (Mac) and choose Close. Alternatively, you can choose Close or Close All in the Perform Action drop down menu.
3. Launch a copy of FileMaker Pro and open a database
4. Go to File > Manage (FMP 9) or File > Define (FMP 7-8.5) and click on Accounts and Privileges
5. You can click on New to add user accounts
Hope this helps. Let me know if there is anything else I can clarify for you.